IDWeek 2021: C diff Clinical Outcomes Unchanged after 2017 IDSA Guideline Update

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Use of vancomycin vs metronidazole increased as first line treatment for Clostridioides difficile infection after publication of the 2017 update to the Infectious Disease Society of America (IDSA) clinical practice guideline for C. difficile, but new research reveals that clinical outcomes did not improve between the pre- and post-update periods. The findings were presented virtually at IDWeek 2021, held September 29 – October 3, 2021.

Publication of the 2017 CDI guideline update was notable for the “phasing out” of metronidazole as first-line treatment and the recommendation for use of vancomycin or fidaxomicin instead, note study authors led by Erik Dubberke, MD, MSPH, professor of medicine, Washington University, in St Louis.

To better understand the impact of the new guideline recommendation, Dubberke and colleagues analyzed changes in antibiotic use and clinical outcomes among Medicare beneficiaries with CDI between before and after the guideline update.

For the pre/post comparison, they conducted a retrospective claims analysis of national Medicare claims data from 2016-2018. The 2 study samples included continuously eligible fee-for-service Medicare beneficiaries aged ³66 years with a new CDI diagnosis that was followed by a filled prescription for an antibiotic in the pre-period (04/01/2017 - 09/30/2017) and post-period (04/01/2018-09/30/2018).

Primary outcomes of interest were: Type of CDI antibiotic received, sustained response, and CDI recurrence. Investigators compared pre- vs post-period outcomes using multivariable regression, controlling for potentially confounding sociodemographic and clinical factors.

There were 7,389 participants in the pre-guideline sample and 7,746 in the post-guideline sample. Characteristics of the groups were similar—59% aged >75 years, 32% men.

Investigators found that after the guideline update, absolute rates of metronidazole use declined 27.7% (relative change [RC] -34.1%, p<.001) and rates of vancomycin use increased 26.9% (RC +150.2%, p< 0.001) (Figure).

While fidaxomicin use increased 0.8% (RC +87.8%, p<.001) from pre- to post-guideline update, overall use remained low, at 1.63%.

The authors write that it was “surprising” to find no improvement in clinical outcomes between the pre- and post-periods. Overall sustained medication response rates decreased (odds ratio [OR]: 0.93, p=0.0197) and overall CDI recurrence rates increased (OR: 1.13, p=0.0018) slightly in the post- vs pre-period, even after adjustment.

When data were analyzed by type of antibiotic used before and after, outcomes with vancomycin (55.0% and 35.1%) were similar to those with metronidazole (54.2% and 33.0%). Fidaxomicin, on the other hand, had higher sustained response and lower CDI recurrence rates (71.4% and 20.9%).

As was the intention after the 2017 IDSA CDI guideline update, use of vancomycin increased substantially and metronidazole use decreased. Study authors found that the fidaxomicin use rates remained low (<2%) despite its recommendation for first-line therapy. But even with the shift to higher use of vancomycin, overall CDI outcomes did not improve post-guideline update. Researchers suggest a possible reason—that vancomycin treatment was not associated with meaningfully improved outcomes relative to metronidazole.

They also point out, in conclusion, that improved outcomes seen with fidaxomicin relative to both vancomycin and metronidazole suggest potential benefits from its greater use in the Medicare population.

The study abstract will be presented during the IDWeek 2021 oral abstract session titled Challenges in C difficile by Dr Dubberke.

Source: Dubberke ER, Puckett JT, Kamal-Bahl S, et al . Real-world challenges in Clostridioides difficile infection (CDI) treatment and utilization and clnical outcomes associated with updated 2017 IDSA Guidelines among Medicare beneficiaries in the U.S. OR-15